Low inertia impact print head

ABSTRACT

A logic operated typewriter including a print head that has low inertia individually moving character-bearing fonts in a driven print wheel. The character-bearing fonts are magnetically retained at the periphery of the wheel. Magnetic count means are provided which are associated with each of the fonts to enable font selection by counting from a predetermined start of counting location on the wheel to select a particular font for impacting same against the typewriter platen so as to make a printed character. A magnetic head is used to count the markers on the print wheel and a magnetic hammer is used to impact each particular font selected.

United States Patent [1 Gerry Oct. 22, 1974 LOW INERTIA IMPACT PRINT HEAD {76] Inventor: Martin E. Gerry, 13452 Wihthrope St., Santa Ana, Calif. 92705 221 Filed: June 27,1973

211 Appl.No.:373,97l

Primary Examiner-Robert E. Pulfrey Assistant ExaminerR. T. Rader [57} ABSTRACT A logic operated typewriter including a print head that has low inertia individually moving character-bearing fonts in a driven print wheel. The character-bearing fonts are magnetically retained at the periphery of the wheel. Magnetic count means are provided which are associated with each of the fonts to enable font selection by counting from a predetermined start of counting location on the wheel to select a particular font for impacting same against the typewriter platen so as to make a printed character. A magnetic head is used to count the markers on the print wheel and a magnetic hammer is used to impact each particular font selected.

7 Claims, 7 Drawing Figures PAIENIEBnmzamu 3,842,950

m1 ear 2 72 Fl ca. 6

FIG.7

1 LOW INERTIA IMPACT PRINT HEAD BACKGROUND OF THE INVENTION This invention is in the field of impact print heads magnetically actuated wherein the characters are positioned about the periphery of a motor driven wheel and electronically selected.

Print heads are normally part of a typewriter carriage so that when the head is actuated and a character is printed on paper resting against a typewriter platen, the carriage is advanced to the next position for imprinting the next character on the paper.

For the most part, where one character at a time is printed, the prior art utilizes print heads that are massive and hence have high inertia slowing down the print speed. This is particularly troublesome where conservation of time is necessary such as in connection with use of a printer as part of a computer terminal.

Other disadvantages of prior art print heads is that it is not possible to read the last few characters printed due to the fact that the print wheel or belt containing print characters cause visual obstruction of such last printed characters, thus making it impossible for a typewriter having these prior art print heads from being used as an office machine which use would be most advantageous, as interlocking of typewriter print bars is impossible.

SUMMARY OF THE INVENTION It is therefore an object of this invention to provide a print head that would be simple in structure and highly reliable in operation, and at the same time reduce the inertia of character-bearing fonts so as to increase the printing speed, and make feasible a simple typewriter with built-in electronic logic at reduced cost.

Accordingly, a print head is provided that comprises a driven print wheel. The print wheel has retained at its periphery a plurality of character-bearing fonts that are magnetically retained by the wheel. Means associated with each of the fonts provide a count of the fonts from a predetermined start location at the wheel periphery so as to enable selection of a particular font, and magnetic means are provided for moving the selected font against the typewriter platen.

In one instance, the fonts are retained in apertures extending from the wheel periphery radially toward the center of the wheel and are magnetically held therein to magnetizable members until overcome by a pulse from an external electromagnet upon selection of a particular font.

In another instance, the fonts are pivotably held in apertures at the periphery of the wheel to a magnetizable member associated with each font and peripherally attached to the print wheel. Upon electronic font selection, an electromagnet of sufficient strength is energized to overcome the magnetic bias holding the particular font selected providing magnetic impact upon the font to pivot same against the typewriter platen.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of a typewriter carriage containing a motor driven print head in accordance with this invention.

FIG. 2 is atop plan view of the print head of FIG. I.

FIG. 3 is a cross-section view taken at plane 3-3 of FIG. 2 with some details of font actuation magnet and shaft of motor that drives the print head.

FIG. 4 is a plan top view ofa modified print head in accordance with this invention wherein each font is individually pivotably magnetically actuated.

FIG. 5 is a cross-section view taken at plane 5-5 of FIG. 4.

FIG. 6 is a perspective view of an individual character font as used in the print head of FIG. 4.

FIG. 7 is a perspective view of a double extension marker held in the print head of FIG. 4 at location where pulse counting commences.

DETAILED DESCRIPTION Referring to FIG. 1, the carriage of electronically actuated typewriter is shown at 10 including the print head, motor drive, font actuator or magnetic hammer, and font selection means.

The typewriter itself and method of translating the carriage thereof is not shown as this is conventional in the art. However the carriage is guided on guide bars (not shown) which extend across the width of the typewriter, one guide bar extending through aperture pair 12 and another guide bar extending though aperture pair 13 of bracket 11.

Motor 14 is attached to the base of bracket II with leads l5 and 16 thereof extending through aperture 17 of the bracket. Shaft 18 of motor 14 has a narrowed portion 19 at the upper portion of the shaft so that the font-bearing head may be mounted at its center, seating itself on the flanged (wide) portion of the shaft. The shaft may also have a keyway with a corresponding keyed aperture at the central aperture of the print head, if desired. But inasmuch as there is substantially little load upon the drive motor due to light weight of the print head, a keyway is not absolutely necessary to prevent slippage of the print head. However, some sort of retaining means for the print head such as nut 20 threaded on narrowed portion 19 of the motor shaft will hold the print head to the shaft during rotation thereof.

A plurality of apertures radially extending from the outer periphery of print head 30 are designated as at 50. Except for aperture 31 that is without font therein, all other apertures 50 have fonts with alpha-numeric characters therein about the entire periphery of print head 30, although only a few such characters are illustrated. Aperture 31 is the location at which magnetic head 34 starts counting pulses. For recognition of the starting point of the count, two closely spaced lines of magnetic materal are affixed at the periphery of the print head as at 35. All characters have single magnetic lines as designators thereof such as at 36. It can be seen that if rotation of head 30 is as shown by arrow 37, the magnetic head 34 will receive the double closely spaced pulse first to start the count, and the character selected for impact position will cause motor I4 to stop the head rotation at such imprint position in accordance with the pulse count assigned to the particular character which is obtained when head 34 is connected by means of wires 41 and 42 to the system of logic (not shown) so as to recognize and count the pulses and en ergize magnetic hammer 38 by exciting the coil thereof due to making connection of wires 39 and 40 through the logic system, so as to move the character font against the typewriter ribbon and/or paper resting against the typewriter platen.

The method of pulse coding and selection of characters and stopping the print head rotation at the print position in accordance with the font selected and actuating the magnetic hammer, need not be discussed herein as it is part of the prior art. For instance, the

logic used for these functions and completely applicable to this print head and carriage motion is discussed completely in the Maintenance Manual for General Electric Keyboard Printer, Model Terminet 3O published in 1970 by the General Electric Company.

Head 34 is mounted to the vertical side portion of the carriage bracket and stationary magnetic hammer 38 is mounted to the base of the carriage bracket.

Referring to FIG. 2, several fonts 43 and their corresponding soft iron bars 44 are shown, wherein bars 44 are embedded in print head 30. Head mounting aperture is shown at 45. It is estimated that all upper and lower case letters and numbers and other special characters can be obtained by a 4 center-to-center spacing between fonts.

Referring to FIG. 3, the cross-section view of the print head clearly shows the advantage and simplicity of this print head.

Print head 30 can be molded or a single integral tef- Ion circular member in which soft iron members as at 44 are molded into the teflon. Members 44 each have a pole face as at 46 for providing a convenient magnetic path due to magnetic flux created by magnetic hammer 38 when the selected font is in the print position and hammer 38 is momentarily energized through the logic system.

It is possible for convenience of manufacture to make the print head in several laminated circular members such as 47, 48 and 49. These members however may also be machined or molded out of brass, aluminum or other non-magnetic materials.

Whichever way head 30 is fabricated, radially extending apertures for each font as at 50 are provided. Since each font 43 is made of a permanent magnet, it is normally attracted to soft iron member 44. However during activation of hammer 38, magnetic flux will pass through soft iron member 44 and set up like magnetic polarities between points of cooperation of the font and the soft iron member of sufficiently large magnitude to overcome the magnetic attraction and repel the font against the typewriter platen and any ribbon in between for impacting a character on the paper in the typewriter. The font extends normally only about onefourth inch and will be quickly withdrawn into the aperture at 50 as soon as hammer 38 is deenergized by the logic and before the logic causes motor 14 to be energized to again rotate head 30.

Referring to FIGS. 4, 5, 6 and 7, another version of the print head is shown at 60 comprising a disk 61 having a central 62 for mounting on the motor shaft in similar manner as hereinbefore described for head 30, and a series of slotted peripheral openings 63 every 4 (but only two slots are shown for simplicity of illustration) about the periphery of the disk, except for one slotted opening from which the pulse count starts, designated at 64. Disk 6| may be made of teflon. nylon, any plastic material or any non-magnetic metal.

Each of slots 63 has a pivotable font retained therein by its pivot pins 66 held in depressions in the sidewalls of slots 63. Fonts 65 each have extensions 72 that extend below disk 61. Each of the fonts has a typeface that is angled with respect to the font body so that in its operative movement to strike the typewriter platen the type face will strike the platen suface tangentially with its full type face.

Slot 64 normally has a stationary (non-pivotable) blank font therein or optionally only the lower extension of the font, which lower extension is a double layer of magnetic sheets with a plastic insulator therebetween and serves as a double closely spaced magnetic marker to indicate the start count location on the print head. It follows that the extensions of each of the fonts will serve as single magnetic markers to provide a single pulse each to head 34 as disk 61 is rotated. It is obvious that all fonts and extensions would be of permanently magnetized material.

Magnetizable members 67 are affixed to the disk behind each of slots 63 for providing magnetic bias or at traction of each font thereto, the surface opposite the font face being being magnetically held to one end of member 67. Slot 64 need not have any member such as 67 affixed behind it since the double extension 68 is fixedly held therein. Extension 68 comprises portions 69 and plastic insulator 70 therebetween. Since most of extension 68 is below the surface of disk 61, head 34 may sense the double pulse provided by permanently magnetized portions 69 thereof.

An electromagnet consisting of a mechanically stationary magnetic hammer is provided at 71 with coil thereof connected to the logic circuitry as stated in connection with discussion of the logic in connection with FIGS. 1-3. The coil of magnet 71 is similarly energized as hammer 38 of FIGS. 1-3 for actuating the magnetic hammer and for actuating the selected font by magnetic repulsion action provided against the surface of the font opposite the character face. The magnetic field of magnet 71 is sufficiently strong to temporarily overcome the magnetic bias or attraction of the magnetized font against member 67. The magnetic hammer action causes the particular font selected to be pivoted at pivot points 66 and to have the face thereof with the character thereon strike the paper against the typewriter platen and any ribbon therebetween or directly if a self inking wheel is employed.

Magnetic hammer 71 is only momentarily energized so that the action of pivotal motion of the font and re turn to its normal position with the font head against member 67 will be rapid.

In view of the low inertia needed to overcome the magnetic holding bias of the font in print head 30 and the low inertia to provide pivoting action of print head 60, it is estimated that the printing speed could be substantially increased over conventional impact print heads. It is also obvious that the print wheels are easily interchangeable so that a pluraltity of extra print wheels with different character forms and even different characters used in foreign languages could be used by the same typewriter.

I claim:

1. A print head, comprising in combination:

a print wheel;

character-bearing permanently magnetized fonts magnetically retained at the periphery of said wheel;

a stationary hammer periodically magnetically couplcd to the fonts for selectively releasing said fonts;

5 6 an individual non-permanently magnetizable mem- 4. The print head of claim 2, wherein the stationary her, one said member associated with each of the hammer is an electromagnet. fonts, which is radially attached to the print wheel 5, Th im h ad f claim 1, wherein; and intermediately positioned between the hamh f t are k d;

and fonts Periodically during Q 'f of the 5 the print wheel has said character-bearing fonts pivwhee]: h of h fonts eihlbmng reducfad otably attached at its periphery substantially at a moment of inertia during magnetic release from its central poim between the ends of each of Said ff gii l g f s I for enabl Se! n fonts, each of said fonts being magnetically reea S n eg I a ee mg 6 tained by its associated member; and

' l 2 i gfigiz 1 wherein m the means integral with said wheel are magnetic porthe print wheel comprises a plurality of apertures ex- Hons of sald fonts I I tending radially about its periphery for retaining The l head of Clam mcludmg magflenc said fonts therein one fem per aperture; and head magnetically coupled to said magnetic portions. the means integral with said wheel are magnetic markers. 7. The print head of claim 5, wherein the stationary 3. The print head of claim 2, including a magnetic hammer is an eiectromagneti head magnetically coupled to said markers.

UNITED STATES PATENT OFFICE m CERTIFICATE OF CORRECTION Patent: No. 3,842,960 Dated October 22, 1974 Inventofls) Martin ry It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

comlaine 5'7:

Change "a central 62" to read a central aperture 62 Signed and sealed this 7th day of January 1975.

(SEAL) Attest: r

McCOY II. GIBSON JR. C. MARSHALL DANN Acts-sting Officer Commissioner of Patents 

1. A print head, comprising in combination: a print wheel; character-bearing permanently magnetized fonts magnetically retained at the periphery of said wheel; a stationary hammer periodically magnetically coupled to the fonts for selectively releasing said fonts; an individual non-permanently magnetizable member, one said member associated with each of the fonts, which is radially attached to the print wheel and intermediately positioned between the hammer and fonts periodically during rotation of the print wheel, each of the fonts exhibiting reduced moment of inertia during magnetic release from its associated member; and means integral with said wheel for enabling selection of a particular font.
 2. The print head of claim 1, wherein: the print wheel comprises a plurality of apertures extending radially about its periphery for retaining said fonts therein, one font per aperture; and the means integral with said wheel are magnetic markers.
 3. The print head of claim 2, including a magnetic head magnetically coupled to said markers.
 4. The print head of claim 2, wherein the stationary hammer is an electromagnet.
 5. The print head of claim 1, wherein: the fonts are elongated; the print wheel has said character-bearing fonts pivotably attached at its periphery substantially at a central point between the ends of each of said fonts, each of said fonts being magnetically retained by its associated member; and the means integral with said wheel are magnetic portions of said fonts.
 6. The print head of claim 5, including a magnetic head magnetically coupled to said magnetic portions.
 7. The print head of claim 5, wherein the stationary hammer is an electromagnet. 